The present invention concerns bismuth dithiocarbamate compounds. More particularly, the invention relates to a novel process for preparing such compounds.
Classically, polyvalent metal salts of dithiocarbamates are prepared by reacting a primary or secondary amine with carbon disulfide and alkali metal hydroxide to form a water soluble intermediate dithiocarbamate salt. This intermediate is reacted with an inorganic polyvalent metal salt to obtain the desired metal dithiocarbamate, often insoluble in water.
It is also known to form polyvalent metal dithiocarbamates by directly reacting primary or secondary amine, carbon disulfide and oxide or hydroxide of the polyvalent metal as described in U.S. Pat. No. 2,492,314.
In another method described in U.S. Pat. No. 2,480,823, polyvalent metal derivatives of organic compounds containing a replaceable hydrogen, e.g. the group -CSSH may be obtained by reacting an inorganic metal salt in liquid ammonia.
Although most polyvalent metal dithiocarbamates can be prepared in economic yields, an exception is bismuth dithiocarbamates. The prior art methods give low yields, even when ammonium media or nitrate salt is employed.
Unexpectedly, it has been discovered that high yields of bismuth dithiocarbamates are obtained by employing a method based on an exchange reaction that is environmentally sound.